Wheel speed estimation method and system under wheel speed sensor failure

Abstract

A wheel speed estimation method and system under wheel speed sensor failure, the method comprising: when a wheel speed sensor failure occurs, determining the failure type of the faulty sensor; if only an abnormal type failure exists, calculating a corrected wheel speed according to the remaining wheel speeds other than the maximum and minimum wheel speeds in the current failure detection period, and combining the corrected wheel speed with the wheel speed of the last failure detection period corresponding to the abnormal type sensor to calculate the estimated wheel speed of the abnormal type sensor; if an invalid type failure exists, and the number of invalid type sensors is less than the number of vehicle sensors, taking the average of the wheel speeds measured by the non-invalid type sensors as the estimated wheel speed of each invalid type sensor; if the number of invalid type sensors is equal to the number of vehicle sensors, combining the wheel speed of the last failure detection period corresponding to the invalid type sensor and the change amount of the vehicle speed in the last failure detection period to calculate the estimated wheel speed of the invalid type sensor. The present application effectively avoids the loss of wheel speed caused by sensor failure and improves the accuracy of wheel speed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobiles, in particular to a wheel speed estimation method and system under wheel speed sensor failure. BACKGROUND

[0002] As a kind of line control brake system, the vehicle body stability control system (Electronic Stability Controller, ESC) is an electronic control device developed to improve the convenience of operation of the driver and the safety of driving. Wheel speed is an important vehicle state parameter required to be identified in the ESC software dynamics control architecture. ESC calculates parameters such as vehicle speed, target slip ratio, target braking torque, target driving torque by receiving wheel speed signals, and improves vehicle lateral and longitudinal stability.

[0003] Generally, low slip ratio means that the vehicle has good grip and stable driving, and high slip ratio means that the wheel has a large degree of slip, and the vehicle may lose stability, increasing the risk of side slip or spin. If the wheel speed of a certain wheel is abnormal (for example, wheel slip), it will cause the slip ratio of the wheel to increase, thereby affecting the traction and handling of the vehicle, especially on wet or icy road surfaces, the change of wheel speed and slip ratio has a more significant impact on vehicle control. The ESC system calculates the slip ratio of the vehicle by monitoring the wheel speed, and if it detects that the slip ratio of a certain wheel is too large, the system will intervene to brake or adjust the power output to reduce the slip ratio, thereby restoring the stability of the vehicle.

[0004] However, in reality, the wheel speed sensor as a weak electrical system may be disturbed by electromagnetic interference generated by other systems or by other environmental factors, and the failure rate of the wheel speed sensor accounts for 30% of the failure rate of the ESC. Wheel speed sensor failure will cause the ESC system to be unable to correctly obtain the wheel speed information, so as to accurately judge the slip ratio. When the correct wheel speed and slip ratio data cannot be obtained, the system cannot effectively intervene, and unnecessary intervention (such as incorrectly applying the brake) may occur, or even the control of vehicle stability may be lost, especially under conditions of sharp turns or wet road surfaces, increasing the risk of driving.

[0005] Therefore, a method is needed to estimate the wheel speed corresponding to the failed wheel speed sensor to solve the technical problems of wheel speed loss and inaccurate measured wheel speed caused by wheel speed sensor failure. SUMMARY

[0006] The present application provides a wheel speed estimation method and system under wheel speed sensor failure, which can solve the technical problems of wheel speed loss and inaccurate measured wheel speed caused by wheel speed sensor failure.

[0007] To achieve the above objectives, in a first aspect, the present application provides a method for estimating wheel speed when a wheel speed sensor fails, the method comprising:

[0008] When a wheel speed sensor fault occurs, determine the fault type of the faulty sensor.

[0009] If only an abnormal fault exists, the corrected wheel speed is calculated based on the remaining wheel speeds in the current fault detection cycle except the maximum wheel speed and the minimum wheel speed. The estimated wheel speed of the abnormal sensor is calculated by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor.

[0010] If there is a failure type fault and the number of failure type sensors is less than the number of sensors in the entire vehicle, the average value of the wheel speeds measured by the non-failure type sensors shall be used as the estimated wheel speed of each failure type sensor; if the number of failure type sensors is equal to the number of sensors in the entire vehicle, the estimated wheel speed of the failure type sensor shall be calculated based on the wheel speed corresponding to the previous fault detection cycle of the failure type sensor and the change in the vehicle speed in the previous fault detection cycle.

[0011] Furthermore, in one embodiment, the failure type fault refers to:

[0012] The sensor is in open circuit or short circuit state. The sensor in each state cannot output wheel speed.

[0013] Each state is determined by the analog voltage of the sensor and the preset voltage threshold range of each state.

[0014] Furthermore, in one embodiment, the abnormal fault includes:

[0015] The wheel speed exceeds the normal vehicle speed range, the absolute value of the wheel speed fluctuation amplitude is greater than the preset wheel speed fluctuation threshold, the vehicle speed is greater than the preset vehicle speed and the wheel speed is less than the preset wheel speed, the number of wheel pulses is not within the expected range, and the absolute value of the change rate of the wheel speed between the current fault detection cycle and the previous fault detection cycle is greater than the preset change rate absolute value threshold; the abnormal sensor has wheel speed output, but the output value is abnormal.

[0016] Furthermore, in one embodiment, the step of calculating the corrected wheel speed based on the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle includes:

[0017] The credibility of each wheel speed in the current fault detection cycle is determined according to the preset fuzzy rules.

[0018] The remaining wheel speeds of the vehicle except the maximum wheel speed and the minimum wheel speed are regarded as normal wheel speeds, and the corrected wheel speeds are calculated based on the normal wheel speeds and their reliability.

[0019] Further, in an embodiment, the method for calculating the estimated wheel speed of the abnormal sensor comprises:

[0020] According to the reliability of the wheel speed of the whole vehicle, the corresponding weight coefficient is calculated.

[0021] The linear difference method is used to calculate the estimated wheel speed of the corresponding abnormal sensor by combining the corrected wheel speed, the wheel speed of the last failure detection period, and the weight coefficient.

[0022] Further, in an embodiment, if there is a failure type fault, only the failure type sensor exists, and the remaining non-failure type sensors are fault-free sensors. When the number of failure type sensors is less than the number of sensors of the whole vehicle, the average value of the wheel speeds of the fault-free sensors is taken as the estimated wheel speed of each failure type sensor.

[0023] Further, in an embodiment, if there is a failure type fault, both failure type sensors and abnormal sensors exist. When the number of failure type sensors is less than the number of sensors of the whole vehicle, the average value of the wheel speeds corresponding to the sensors other than the failure type sensors is taken as the estimated wheel speed of each failure type sensor.

[0024] Further, in an embodiment, the average value of the wheel speeds corresponding to the sensors other than the failure type sensors is taken as the estimated wheel speed of each failure type sensor, comprising:

[0025] If all the sensors other than the failure type sensors are abnormal sensors, the average value of the estimated wheel speeds of the abnormal sensors is taken as the estimated wheel speed of each failure type sensor.

[0026] If there are abnormal sensors and fault-free sensors other than the failure type sensors, the average value of the estimated wheel speeds of the abnormal sensors and the wheel speeds of the fault-free sensors is taken as the estimated wheel speed of each failure type sensor.

[0027] Further, in an embodiment, the method for calculating the estimated wheel speed of the failure type sensor by combining the wheel speed of the last failure detection period corresponding to the failure type sensor and the change amount of the vehicle speed of the last failure detection period comprises:

[0028] The vehicle acceleration of the last failure detection period is obtained.

[0029] The estimated wheel speed of the corresponding failure type sensor is calculated by combining the wheel speed of the last failure detection period, the vehicle acceleration of the last failure detection period, and the failure detection period.

[0030] In a second aspect, based on the above-mentioned wheel speed estimation method under the wheel speed sensor fault, the application provides a wheel speed estimation system of a wheel speed estimation method under a wheel speed sensor fault, the system comprising:

[0031] a judging module configured to judge the fault type of the faulty sensor when the wheel speed sensor fault occurs.

[0032] an estimating module configured to, when only the abnormal fault exists, calculate a corrected wheel speed according to the wheel speeds other than the maximum wheel speed and the minimum wheel speed in the current fault detection period, and calculate the estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the abnormal sensor in the previous fault detection period; further configured to, when the failure fault exists, and the number of the failure sensors is less than the number of the vehicle sensors, take the average of the wheel speeds measured by the non-failure sensors as the estimated wheel speed of each failure sensor; further configured to, when the failure fault exists, and the number of the failure sensors is equal to the number of the vehicle sensors, calculate the estimated wheel speed of the failure sensor by combining the wheel speed of the failure sensor in the previous fault detection period and the vehicle speed variation in the previous fault detection period.

[0033] The technical scheme provided by the embodiment of the present application has the following beneficial effects:

[0034] The present application judges the fault type of the faulty sensor when the wheel speed sensor fault occurs, and designs a corresponding wheel speed estimation algorithm for different types of faults to calculate the wheel speed corresponding to the faulty sensor; if only the abnormal fault exists, a corrected wheel speed is calculated according to the wheel speeds other than the maximum wheel speed and the minimum wheel speed in the current fault detection period, and the estimated wheel speed of the abnormal sensor is calculated by combining the corrected wheel speed with the wheel speed of the abnormal sensor in the previous fault detection period; if the failure fault exists, and the number of the failure sensors is less than the number of the vehicle sensors, the average of the wheel speeds measured by the non-failure sensors is taken as the estimated wheel speed of each failure sensor; if the number of the failure sensors is equal to the number of the vehicle sensors, the estimated wheel speed of the failure sensor is calculated by combining the wheel speed of the failure sensor in the previous fault detection period and the vehicle speed variation in the previous fault detection period. The wheel speed loss caused by the wheel speed sensor no-output fault is effectively avoided, and the accuracy of the wheel speed reading under the wheel speed sensor abnormal output fault is improved, thereby effectively improving the correctness of the slip rate calculation and enhancing the control of the vehicle stability. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The flowchart of the wheel speed estimation method under the wheel speed sensor fault in the embodiment of the present application.

[0036] Figure 2 The membership function diagram of the fuzzy subset in the embodiment of the present application.

[0037] Figure 3 The wheel speed estimation method when the failure fault exists in the embodiment of the present application.

[0038] Figure 4Block diagram of a wheel speed estimation system under a wheel speed sensor failure according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0041] In a first aspect, an embodiment of the present application provides a method for estimating wheel speed when a wheel speed sensor fails.

[0042] In one embodiment, see Figure 1 As shown, the above wheel speed estimation method includes:

[0043] S1. Wheel speed sensor failure occurs.

[0044] S2. Determine the fault type of the faulty sensor; if only an abnormal fault exists, proceed to S3; if a failure fault exists, proceed to S4.

[0045] S3. Calculate a corrected wheel speed based on the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle, and calculate an estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor.

[0046] S4: Determine the relationship between the number of failed sensors and the number of sensors in the vehicle. If the number of failed sensors is less than the number of sensors in the vehicle, proceed to S5; if the number of failed sensors is equal to the number of sensors in the vehicle, proceed to S6.

[0047] S5. Taking the average of the wheel speeds measured by the non-failure sensors as the estimated wheel speed of each failure sensor.

[0048] S6. Calculate the estimated wheel speed of the failed sensor by combining the wheel speed corresponding to the failed sensor in the previous fault detection period and the change in vehicle speed in the previous fault detection period.

[0049] When a wheel speed sensor malfunctions, this application determines the fault type of the sensor, determining whether it is simply an abnormality or a failure. Based on the different types of faults, corresponding wheel speed estimation algorithms are designed to calculate the wheel speed corresponding to the faulty sensor. This application effectively avoids missing wheel speeds caused by a wheel speed sensor with no output value and improves the accuracy of wheel speed readings when the wheel speed sensor has an abnormal output value, thereby effectively improving the accuracy of slip calculations and enhancing vehicle stability control. Furthermore, this method only requires software control logic to determine the wheel speed sensor fault type and calculate the wheel speed corresponding to the fault type using the designed estimation algorithm, without requiring any hardware development.

[0050] Furthermore, in one embodiment, in step S3, the corrected wheel speed is calculated based on the remaining wheel speeds in the current fault detection cycle except for the maximum wheel speed and the minimum wheel speed, and the estimated wheel speed of the abnormal sensor is calculated by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor, including:

[0051] S31. Determine the credibility of each wheel speed in the current fault detection cycle according to a preset fuzzy rule.

[0052] S32: The remaining wheel speeds of the vehicle, except for the maximum wheel speed and the minimum wheel speed, are regarded as normal wheel speeds, and the corrected wheel speeds are calculated based on the normal wheel speeds and their reliability. Specifically:

[0053] Sort the four wheel speeds of the vehicle by size and find the second and third wheel speeds, which are the normal wheel speeds.

[0054] The corrected wheel speed is calculated using the normal wheel speed and its reliability, according to the following calculation formula: .

[0055] in, Indicates the corrected wheel speed, Indicates the number of normal wheel speeds, Indicates the reliability of normal wheel speed, Indicates the Normal wheel speed, The calculation formula is: ,in, is the cumulative number of pulses in the current fault detection cycle, is the number of teeth on the ring gear, is the wheel radius, The time length corresponding to a fault detection cycle.

[0056] S33. Calculate the corresponding weight coefficient based on the credibility of each wheel speed of the vehicle. The formula is: ,in, Indicates the position of the wheel, =1, 2, 3, 4 represent the front left wheel, front right wheel, rear left wheel and rear right wheel respectively, Indicates the reliability of the wheel speed of the vehicle.

[0057] S34. Combine the corrected wheel speed, the wheel speed in the previous fault detection cycle, and the weight coefficient to calculate the estimated wheel speed of the corresponding abnormal sensor using the linear difference method. The formula is: ,in, Indicates the weight coefficient corresponding to the abnormal sensor in the current fault detection cycle, Indicates the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor.

[0058] In this embodiment, when only an abnormal fault exists during a fault detection cycle—that is, the sensor is able to output wheel speed values ​​but the output wheel speed values ​​are abnormal—the calculated corrected wheel speed is combined with the wheel speed corresponding to the abnormal sensor during the previous fault detection cycle to calculate the wheel speed corresponding to the abnormal sensor during that fault detection cycle using an estimation algorithm. This ensures that even when a wheel speed sensor has an abnormal wheel speed output, the wheel speed can still be obtained with relative accuracy.

[0059] Furthermore, in one embodiment, the specific steps in the above step S31 include:

[0060] S311. Define fuzzy rule input variables, which include 、 、 、 、 、 as well as , the meaning of each input variable is:

[0061] : Describes the absolute value of the change in the speed of a single wheel per unit time, that is, the acceleration (or deceleration) of the vehicle, which is directly related to the acceleration or deceleration process of the vehicle.

[0062] : Describes the absolute value of the acceleration gradient of a single wheel, that is, the amplitude of change during acceleration or deceleration.

[0063] : Describes the absolute value of the rate of change of a single wheel speed between the current cycle and the previous cycle. If the wheel speed fluctuation rate is large, it means that there may be some irregular changes in the vehicle during driving.

[0064] : Describes the absolute value of the wheel speed fluctuation rate of a single wheel, which refers to the fluctuation amplitude of the wheel speed within a certain period of time. If the wheel speed fluctuation rate is large, it means that there may be some rapid fluctuations during the vehicle's driving process.

[0065] : Describes the number of wheels under ABS control during vehicle instability.

[0066] : Describes the number of wheels under VDC control during vehicle instability.

[0067] : Describes the number of wheels under TCS control during vehicle instability.

[0068] S312. Formulate fuzzy rules:

[0069] Rule 1: The smaller the values ​​of the wheel speed fault counter OutRange_cnt, noise fault counter Noise_cnt, wheel speed loss fault counter WhlSpdMiss_cnt, pulse fault counter Pluse_cnt, tooth missing fault counter Teeth_cnt, open circuit fault counter Open_cnt, and short circuit fault counter Short_cnt, the higher the wheel speed stability and the greater the corresponding credibility.

[0070] Rule 2: When driving steadily The smaller the value of The smaller the value, the higher the wheel stability, and the corresponding credibility The bigger.

[0071] Rule 3, The smaller it is, the higher the wheel speed stability is, and the corresponding reliability is The larger the value, the greater the wheel acceleration changes dramatically in a short period of time, which means that the operation during driving is very intense, and the corresponding reliability The lower it is.

[0072] Rule 4: When the vehicle is under normal braking conditions, the fewer wheels under ABS / VDC / TCS control, the higher the wheel speed stability and the greater the corresponding credibility.

[0073] S313, establish the following for the input fuzzy variables: Figure 2 The fuzzy subsets shown in the figure have fuzzy languages ​​S (Small), M (Medium), and L (Large). The fuzzy variables for each input vary depending on the domain parameters. The parameters for each fuzzy variable are shown in the table below. The selection of fuzzy subset parameters requires extensive experimental data.

[0074]

[0075] S314. Calculate the membership of the above-mentioned rules 1, 2, 3, 3, and 4 for each wheel speed respectively, and take the maximum value of the membership as the credibility of the corresponding wheel speed.

[0076] Specifically, taking Rule 2 as an example, if ,Pick , , then take and The minimum value is 0.2, if , , then take and The smaller value 0.2 is used as the membership degree of rule 2 Calculate the membership degree of Rule 1, Rule 2, Rule 3, and Rule 4 for each wheel speed 、 、 、 , take the maximum value of the membership degree of each rule as the credibility of the corresponding wheel speed, that is, .

[0077] Furthermore, in one embodiment, the abnormal fault in step S2 includes:

[0078] The wheel speed exceeds the normal vehicle speed range; the absolute value of the wheel speed fluctuation amplitude exceeds the preset wheel speed fluctuation threshold; the vehicle speed exceeds the preset vehicle speed and the wheel speed is less than the preset wheel speed; the number of wheel pulses is outside the expected range; and the absolute value of the rate of change of the wheel speed between the current fault detection cycle and the previous fault detection cycle exceeds the preset absolute value threshold. The abnormal sensor has a wheel speed output, but the output value is abnormal. The preset vehicle speed is greater than the preset wheel speed. In this embodiment, the preset vehicle speed is 15 km / h and the preset wheel speed is 2 km / h.

[0079] The above-mentioned abnormal fault judgment methods include:

[0080] If the wheel speed exceeds the normal range (in this embodiment, the normal wheel speed range is 0 km / h-300 km / h), the value of OutRange_cnt automatically increases from zero. If the wheel speed is within the normal range, the value of OutRange_cnt automatically decreases from zero. If the value of OutRange_cnt is greater than the maximum value of the preset wheel speed fault threshold range, the wheel speed sensor is recorded as faulty. If the value of OutRange_cnt is less than the minimum value of the preset wheel speed fault threshold range, the wheel speed sensor is recorded as not faulty and the value of OutRange_cnt is reset. If the value of OutRange_cnt is within the wheel speed fault threshold range, the wheel speed sensor is recorded as being in the testing state.

[0081] If the absolute value of the wheel speed fluctuation amplitude exceeds the preset wheel speed fluctuation threshold, the wheel speed sensor is judged to be noisy and the value of Noise_cnt automatically increases from zero. If the absolute value of the wheel speed fluctuation amplitude is less than or equal to the preset wheel speed fluctuation threshold, the value of Noise_cnt automatically decreases from zero. If the value of Noise_cnt exceeds the maximum value of the preset noise fault threshold range, the wheel speed sensor is marked as faulty. If the value of Noise_cnt is less than the minimum value of the preset noise fault threshold range, the wheel speed sensor is marked as not faulty and the value of Noise_cnt is reset. If the value of Noise_cnt is within the noise fault threshold range, the wheel speed sensor is marked as being in the testing state.

[0082] If the vehicle is driving without triggering ABS, EBD, or TCS functions, and the vehicle speed is greater than 15 km / h and the wheel speed is less than 2 km / h, the wheel speed is considered lost, and the value of WhlSpdMiss_cnt automatically increases from zero. If the wheel speed is also greater than 15 km / h when the vehicle speed is greater than 15 km / h, the value of WhlSpdMiss_cnt automatically decreases from zero. If the value of WhlSpdMiss_cnt is greater than the maximum value of the preset wheel speed loss fault threshold range, the wheel speed sensor is recorded as faulty. If the value of WhlSpdMiss_cnt is less than the minimum value of the preset wheel speed loss fault threshold range, the wheel speed sensor is recorded as not faulty and the value of WhlSpdMiss_cnt is reset. If the value of WhlSpdMiss_cnt is within the wheel speed loss fault threshold range, the wheel speed sensor is recorded as being in a testing state.

[0083] The number of pulses at each wheel is checked. If the pulse count is outside the preset pulse count range, the value of Pluse_cnt is incremented from zero. If the pulse count is within the preset pulse count range, the value of Pluse_cnt is decremented from zero. If the value of Pluse_cnt is greater than the maximum value of the preset pulse failure threshold range, the wheel speed sensor is marked as faulty. If the value of Pluse_cnt is less than the minimum value of the preset pulse loss fault threshold range, the wheel speed sensor is marked as not faulty and the value of Pluse_cnt is reset. If the value of Pluse_cnt is within the pulse loss fault threshold range, the wheel speed sensor is marked as being tested.

[0084] When the vehicle is driving on a smooth surface and ABS, EBD, TCS, or other functions are not triggered, if the absolute value of the rate of change of wheel speed between the current cycle and the previous cycle is greater than the preset absolute value threshold of the rate of change, a missing tooth occurs and the value of Teeth_cnt automatically increases from zero. If the absolute value of the rate of change of wheel speed between the current cycle and the previous cycle is less than or equal to the preset absolute value threshold of the rate of change, the value of Teeth_cnt automatically decreases from zero. If the value of Teeth_cnt is greater than the maximum value of the preset missing tooth fault threshold range, the wheel speed sensor is recorded as faulty. If the value of Teeth_cnt is less than the minimum value of the preset missing tooth fault threshold range, the wheel speed sensor is recorded as not faulty and the value of Teeth_cnt is reset. If the value of Teeth_cnt is within the missing tooth fault threshold range, the wheel speed sensor is recorded as being in the testing state.

[0085] Further, in one embodiment, see Figure 3 As shown, when a failure type fault exists, the calculation steps for estimating the wheel speed of the failure type sensor include:

[0086] A101. If a failure type fault exists, determine whether the number of failed sensors is less than the number of sensors in the entire vehicle. If so, proceed to step A102; if not, proceed to step A107.

[0087] A102. Determine whether there is an abnormal sensor. If so, proceed to step A103. If not, proceed to step A106.

[0088] A103. Determine whether all sensors except the failed sensor are abnormal. If so, proceed to step A104. If not, proceed to step A105.

[0089] A104. The average value of the estimated wheel speeds of the abnormal sensors is used as the estimated wheel speed of each failed sensor.

[0090] A105. The average of the estimated wheel speed of the abnormal sensor and the wheel speed of the normal sensor is used as the estimated wheel speed of each failed sensor.

[0091] A106. The remaining non-failure sensors are considered to be fault-free sensors, and the average wheel speed of the fault-free sensors is used as the estimated wheel speed of each failure sensor.

[0092] A107. Obtain the vehicle acceleration during the previous fault detection cycle, and calculate the estimated wheel speed of the failed sensor based on the wheel speed during the previous fault detection cycle corresponding to the failed sensor and the change in vehicle speed during the previous fault detection cycle. The formula used is: , Indicates the wheel speed of the last fault detection cycle corresponding to the failed sensor, Indicates the vehicle acceleration during the last fault detection cycle.

[0093] In this embodiment, when a failure-type fault occurs during a fault detection cycle, different wheel speed estimation methods are designed based on the situation. This ensures that even when the wheel speed sensor fails to output a wheel speed value, the wheel speed can still be obtained, effectively avoiding the situation where the wheel speed is missing.

[0094] Furthermore, in one embodiment, the above-mentioned failure-type fault refers to the sensor being in an open circuit state or a short circuit state, and the sensor in the open circuit and short circuit states cannot output the wheel speed; the open circuit and short circuit states are respectively judged by the analog voltage of the sensor and the preset voltage threshold range of each state.

[0095] The judgment methods for the above-mentioned failure types include:

[0096] B101. Read the analog voltage of the wheel speed sensor. (The wheel speed sensor senses the rotation of the wheel, generating a changing magnetic field or electromagnetic induction phenomenon, thereby generating an electrical signal. The signal is then converted into an analog voltage output through circuit processing to reflect the wheel speed.)

[0097] B102. If the analog voltage value is within the preset open-circuit voltage threshold range, the sensor is considered in an open-circuit state (i.e., the signal is disconnected or disconnected), and the value of Open_cnt automatically increases from zero. If the analog voltage value is not within the preset open-circuit voltage threshold range, the value of Open_cnt automatically decreases from zero. If the value of Open_cnt is greater than the maximum value of the preset open-circuit fault threshold range, the wheel speed sensor is considered in a fault state. If the value of Open_cnt is less than the minimum value of the preset open-circuit fault threshold range, the wheel speed sensor is considered in a non-fault state, and the value of Open_cnt is reset. If the value of Open_cnt is within the open-circuit fault threshold range, the wheel speed sensor is considered in a testing state.

[0098] Furthermore, in one embodiment, the open circuit voltage threshold range may be greater than 180V and less than 220V.

[0099] B103. If the analog voltage value is within the preset short-circuit voltage threshold range, a short-circuit state is recorded, i.e., the circuit is shorted to power or ground, and the value of Short_cnt automatically increases from zero. If the analog voltage value is not within the preset short-circuit voltage threshold range, the value of Short_cnt automatically decreases from zero. If the value of Short_cnt is greater than the maximum value of the preset short-circuit fault threshold range, the wheel speed sensor is recorded as faulty. If the value of Short_cnt is less than the minimum value of the preset short-circuit fault threshold range, the wheel speed sensor is recorded as not faulty and the value of Short_cnt is reset. If the value of Short_cnt is within the short-circuit fault threshold range, the wheel speed sensor is recorded as being in the testing state.

[0100] Furthermore, in one embodiment, the short-circuit voltage threshold range may be greater than 230V and less than 280V.

[0101] Furthermore, in one embodiment, if the wheel speed sensor is in a testing state, the credibility of the wheel speed corresponding to the wheel speed sensor in testing needs to be modified to minimize the impact of the abnormal wheel speed signal on the estimation algorithm.

[0102] In a second aspect, based on the above embodiment of the wheel speed estimation method under wheel speed sensor failure, the present application provides an embodiment of a wheel speed estimation system for the wheel speed estimation method under wheel speed sensor failure. Figure 4 As shown, the above system includes a judgment module and an estimation module, specifically:

[0103] The judgment module is used to judge the fault type of the faulty sensor when a wheel speed sensor fault occurs.

[0104] An estimation module is used to calculate the corrected wheel speed based on the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle when only an abnormal fault exists, and to calculate the estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor; it is also used to use the average value of the wheel speeds measured by the non-failure sensors as the estimated wheel speed of each failure sensor when there is a failure fault and the number of failure sensors is less than the number of sensors in the entire vehicle; it is also used to calculate the estimated wheel speed of the failure sensor by combining the wheel speed of the previous fault detection cycle corresponding to the failure sensor and the change in vehicle speed in the previous fault detection cycle when there is a failure fault and the number of failure sensors is equal to the number of sensors in the entire vehicle.

[0105] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0106] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0107] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0108] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0109] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, or the part that contributes to the existing technology, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above and includes a number of instructions for enabling a terminal device to execute the methods described in each embodiment of this application.

[0110] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for estimating wheel speed when a wheel speed sensor fails, characterized in that: The method comprises: When a wheel speed sensor fault occurs, determine the fault type of the faulty sensor; If only an abnormal fault exists, the corrected wheel speed is calculated based on the remaining wheel speeds in the current fault detection cycle except for the maximum and minimum wheel speeds. The estimated wheel speed of the abnormal sensor is calculated by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor. If a failure type fault exists and the number of failed sensors is less than the number of sensors in the vehicle, the average of the wheel speeds measured by the non-failed sensors is used as the estimated wheel speed of each failed sensor. If the number of failed sensors is equal to the number of sensors in the vehicle, the estimated wheel speed of the failed sensor is calculated by combining the wheel speed corresponding to the failed sensor in the previous fault detection cycle and the change in vehicle speed in the previous fault detection cycle. The failure type fault refers to: The sensor is in open circuit or short circuit state. The sensor in each state cannot output wheel speed. Each state is judged by the analog voltage of the sensor and the preset voltage threshold range of each state; The abnormal faults include: The wheel speed exceeds the normal vehicle speed range, the absolute value of the wheel speed fluctuation amplitude is greater than the preset wheel speed fluctuation threshold, the vehicle speed is greater than the preset vehicle speed and the wheel speed is less than the preset wheel speed, the number of wheel pulses is not within the expected range, and the absolute value of the change rate of the wheel speed between the current fault detection cycle and the previous fault detection cycle is greater than the preset change rate absolute value threshold; the abnormal sensor has wheel speed output, but the output value is abnormal.

2. The wheel speed estimation method under wheel speed sensor failure according to claim 1, characterized in that: The calculating of the corrected wheel speed according to the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle includes: Determine the credibility of each wheel speed within the current fault detection cycle according to the preset fuzzy rules; The remaining wheel speeds of the vehicle except the maximum wheel speed and the minimum wheel speed are regarded as normal wheel speeds, and the corrected wheel speeds are calculated based on the normal wheel speeds and their reliability.

3. The wheel speed estimation method under wheel speed sensor failure according to claim 2, characterized in that: The calculating of the estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor includes: Calculate the corresponding weight coefficient according to the credibility of each wheel speed of the vehicle; Combining the corrected wheel speed, the wheel speed of the previous fault detection cycle, and the weight coefficient, the linear difference method is used to calculate the estimated wheel speed of the corresponding abnormal sensor.

4. The wheel speed estimation method under wheel speed sensor failure according to claim 1, characterized in that: If there is a failure type fault, only the failed sensor exists, and the other non-failed sensors are fault-free sensors. When the number of failed sensors is less than the number of sensors in the entire vehicle, the average wheel speed of the fault-free sensors is used as the estimated wheel speed of each failed sensor.

5. The wheel speed estimation method under wheel speed sensor failure according to claim 1, characterized in that: If there is a failure type fault, there are both failed sensors and abnormal sensors. When the number of failed sensors is less than the number of sensors in the entire vehicle, the average wheel speed corresponding to the sensors other than the failed sensors is used as the estimated wheel speed of each failed sensor.

6. The wheel speed estimation method under wheel speed sensor failure according to claim 5, characterized in that: The average of the wheel speeds corresponding to the sensors other than the failed sensor is used as the estimated wheel speed of each failed sensor, including: If all sensors except the failed sensor are abnormal, the average of the estimated wheel speeds of the abnormal sensors is used as the estimated wheel speed of each failed sensor; If there are abnormal sensors and normal sensors in addition to the failed sensors, the average of the estimated wheel speeds of the abnormal sensors and the normal sensors is used as the estimated wheel speed of each failed sensor.

7. The wheel speed estimation method under wheel speed sensor failure according to claim 1, characterized in that: The step of calculating the estimated wheel speed of the failed sensor by combining the wheel speed corresponding to the failed sensor in the previous fault detection period and the change in vehicle speed in the previous fault detection period includes: Obtain the vehicle acceleration during the last fault detection cycle; The estimated wheel speed of the corresponding failed sensor is calculated by combining the wheel speed of the previous fault detection cycle, the vehicle acceleration of the previous fault detection cycle, and the fault detection cycle.

8. A wheel speed estimation system based on the wheel speed estimation method under wheel speed sensor failure according to any one of claims 1 to 7, characterized in that: The system comprises: A judgment module, which is used to judge the fault type of the faulty sensor when a wheel speed sensor fault occurs; An estimation module is used to calculate the corrected wheel speed based on the remaining wheel speeds except the maximum wheel speed and the minimum wheel speed in the current fault detection cycle when only an abnormal fault exists, and to calculate the estimated wheel speed of the abnormal sensor by combining the corrected wheel speed with the wheel speed of the previous fault detection cycle corresponding to the abnormal sensor; it is also used to use the average value of the wheel speeds measured by the non-failure sensors as the estimated wheel speed of each failure sensor when there is a failure fault and the number of failure sensors is less than the number of sensors in the entire vehicle; it is also used to calculate the estimated wheel speed of the failure sensor by combining the wheel speed of the previous fault detection cycle corresponding to the failure sensor and the change in vehicle speed in the previous fault detection cycle when there is a failure fault and the number of failure sensors is equal to the number of sensors in the entire vehicle.

Images